Interrelated power delivery controls – including engine control – Plural engines – Electric engine
Reexamination Certificate
1999-11-08
2001-02-06
Estremsky, Sherry (Department: 3681)
Interrelated power delivery controls, including engine control
Plural engines
Electric engine
C477S062000, C477S063000, C477S174000
Reexamination Certificate
active
06183389
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
This invention relates to a lock-up control system for a torque transmission device with a lock-up clutch that is arranged between a drive source and a drive wheel of a vehicle that has at least a motor or a motor generator in its drive source.
2. Description of Related Art
In a vehicle that has an engine, fuel is combusted within the engine, generating heat energy, and this heat energy is converted to mechanical energy (drive force) to drive the vehicle. With an engine, the driving region at which combustion efficiency is good and high torque can be obtained is limited to a relatively narrow r.p.m. (revolution per minute) range. Therefore, in a vehicle that uses an engine as the drive source, the engine r.p.m. and engine output torque are changed by a transmission depending on a driving condition, and transmitted to the vehicle wheel(s).
Incidentally, in recent years, hybrid vehicles have been proposed that have a different type of drive source, in particular, a motor generator, with objects of conserving the fuel which drives the engine, reducing the noise due to engine revolution, and reducing the exhaust gas that is generated through combustion of the fuel. It is proposed, in these hybrid vehicles, too, to use a transmission and a torque converter with a lock-up clutch between the drive source and the drive wheel(s), the same as in a vehicle that has only an engine as a drive source. For example, there is such a system disclosed in Japanese Laid-Open Application No. 8-168104.
Incidentally, a hybrid vehicle provided with a motor or motor generator as described above can run using the motor or motor generator as a drive source, and since this motor or motor generator has the advantage of having virtually no torque fluctuation as compared to an engine that combusts fuel, it is possible to control the lock-up clutch of a torque converter so as to capitalize on this advantage. However, in existing systems, including the one listed above, lock-up clutch control that adequately capitalizes on the advantage of a motor or motor generator is not necessarily always performed.
SUMMARY OF THE INVENTION
This invention is made in light of the above-described problems, and has an object of, in a vehicle that has at least a motor in its drive source, capitalizing on the advantages of the motor the state in which a torque transmission system (torque converter) with a lock-up clutch that is positioned between a drive source and a drive wheel is operated with the motor as the drive source.
In order to solve the above-described problems, in a first aspect of the invention, a vehicle is provided with an engine, which is driven through fuel combustion, and a motor as drive sources, and has a torque transmission device with a lock-up clutch that is provided between a drive wheel on one side and the engine and motor on the other side. A lock-up clutch control device is provided that controls an engagement state of the lock-up clutch. The lock-up clutch control device changes the content of the engagement control of the lock-up clutch according to the operational state of the drive source.
Additionally, in a second aspect of the invention, in an operational state in which the motor operates as the drive source, the driving region at which the lock-up clutch is engaged is broadened compared to an operational state in which only the engine operates as the drive source.
Additionally, in a third aspect of the invention, in an operational state in which only the motor operates as the drive source, the driving region at which the lock-up clutch is engaged is broadened compared to an operational state in which the engine and motor both operate as drive sources.
Thus, in the first through third aspects of the invention, since the motor is comparatively less apt to generate torque fluctuation than the engine, the vehicle can be driven with the lock-up clutch engaged. In other words, the advantage of the motor can be capitalized upon, i.e., the fact that at a given acceleration and vehicle speed, even if the lock-up clutch cannot be engaged due to torque fluctuation when driving by the engine only, the lock-up clutch can be engaged when operating the motor as a drive source.
In a fourth aspect of the invention, a vehicle is provided with an engine that operates through fuel combustion and a motor as drive sources, and a torque transmission device with a lock-up clutch is provided between a drive wheel on one side and the engine and motor on the other side. A transmission is also provided. A lock-up clutch control device is provided that controls an engagement state of the lock-up clutch. The lock-up clutch control device changes the content of the lock-up clutch engagement control according to an operational state of the drive source at the time of speed changing by the transmission.
Additionally, in a fourth aspect of the invention, the lock-up clutch control device controls the lock-up clutch to be in a half-engaged state in an operational state in which the motor is operating as the drive source at the time of speed changing by the transmission. The lock-up clutch control device controls the lock-up clutch to be in a disengaged state in an operational state in which only the engine is operating as the drive source at the time of speed changing.
Thus, according to the fourth and fifth aspects of the invention, the advantage of the motor can be capitalized upon, i.e., the fact that when the lock-up clutch is engaged and the vehicle is driven by only the engine, speed changing of the transmission, in other words, switching of the various engaging elements in the transmission, must be performed after temporarily disengaging the lock-up clutch, but when operating the motor as a drive source, since the torque variation is small, it is unnecessary to completely disengage the lock-up clutch.
In a sixth aspect of the invention, a vehicle is provided with at least a motor generator as a drive source, and a torque transmission device with a lock-up clutch provided between a drive wheel and the motor generator. The motor generator can supply regenerative braking torque to the drive wheel by functioning as an electrical generator. A lock-up clutch control device is provided that controls an engagement state of the lock-up clutch. During deceleration of the vehicle, the motor generator functions as an electrical generator during deceleration of the vehicle, and the lock-up clutch control device controls an engagement state of the lock-up clutch in order to adjust the deceleration degree during deceleration.
According to the sixth aspect of the invention, regenerative braking torque is applied to a drive wheel by the motor generator during deceleration of the vehicle. It is necessary to change the magnitude of the regenerative braking torque in order to achieve the desired deceleration degree of the vehicle. By appropriately adjusting the engagement state of the lock-up clutch and changing the r.p.m. of the motor generator, the magnitude of the regenerative braking torque can be changed.
REFERENCES:
patent: 5415603 (1995-05-01), Tuzuki et al.
patent: 5562565 (1996-10-01), Moroto et al.
patent: 5735770 (1998-04-01), Omote et al.
patent: 5775449 (1998-07-01), Moroto et al.
patent: 5789823 (1998-08-01), Sherman
patent: 5856709 (1999-01-01), Ibaraki et al.
patent: 5895333 (1999-04-01), Morrisawa et al.
patent: 6070680 (2000-06-01), Oyama
patent: 6081042 (2000-06-01), Tabata et al.
patent: 8-168104 (1996-06-01), None
patent: 9-324666 (1997-12-01), None
Estremsky Sherry
Oliff & Berridg,e PLC
Toyota Jidosha & Kabushiki Kaisha
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